What is the difference between Energy and Power?

Every card you play in Riftbound: the League of Legends trading card game is paid for with runes, and runes make two resources, Energy and Power. The two pay different parts of a cost, and you get them from your runes in two different ways. One way leaves the rune on the board for the next turn, and the other way sends it to the bottom of your Rune Deck.

Power has nothing to do with how strong a unit is. The strength of a unit is its Might, the number next to the sword and shield, and Energy and Power are only ever spent to pay costs.

What is Energy?

Energy pays the number in the top left corner of a card, which is its Energy cost. You get Energy by exhausting a rune: every basic rune can be turned sideways to add 1 Energy. Energy has no domain, so any rune can make the Energy for any card.

An exhausted rune stays on the board and readies again in your next Awaken Phase. Paying Energy therefore costs you nothing beyond the current turn. The number of runes on your board is the most Energy you can make in a turn, unless another card adds Energy or readies your runes.

What is Power?

Power pays the domain symbols stacked under the number, which are the Power cost. Each symbol asks for one Power of that domain. You get Power by recycling a rune: every basic rune can be put on the bottom of your Rune Deck to add 1 Power of its own domain. A Fury Rune gives Fury Power, a Chaos Rune gives Chaos Power, and no rune gives Power of a domain other than its own.

One rune can give both in the same turn. You can exhaust it for Energy first and recycle it afterwards for Power, because an exhausted rune can still be recycled. The other way round does not work, since a recycled rune has already left the board.

Falling Star, a Fury spell, costs 2 Energy and two Fury Power. To play it, you exhaust two runes of any domain and recycle two Fury Runes, and the two Fury Runes you recycle may be the two you exhausted. A Chaos Rune can be one of the two you exhaust, but it cannot pay for a Fury Power.

Why does paying Power cost more than paying Energy?

A rune you exhaust comes back, but a rune you recycle does not. Each Power you pay takes a rune off the board, while you still channel only two new runes a turn.

Say you go first with a Jinx deck of Fury Runes and Chaos Runes. On your third turn you have six runes, if none has been recycled. After Falling Star you have four runes left for that turn, and your next turn starts with six runes instead of eight. A recycled rune is not lost for good: it waits at the bottom of your Rune Deck, and you channel it again once the runes above it are gone.

Most cards ask for one Power or none. The few that ask for three or four, such as Commander Ledros with 6 Energy and four Order Power, take three or four runes off your board at once when runes pay for them.

Does Power have to match the card's domain?

A rune pays only the domain symbols of its own domain. In a deck of Fury Runes and Chaos Runes, the Chaos Runes help pay the Energy of a Fury card but never its Fury symbols. A signature card of two domains accepts either one: Defiant Dance, the Calm and Chaos signature spell of Irelia, costs 1 Energy and one Power that may be Calm or Chaos, so a Calm Rune or a Chaos Rune can pay it.

Some costs ask for Power of any domain instead, which cards show as a swirling rainbow symbol. Hiding a card with Hidden costs one Power of any domain. The extra Power that Deflect asks of an opponent who chooses the unit may be of any domain as well. The extra cost of Accelerate is stricter, since its Power must match a domain of the unit. Some Power works for every domain as well: the Gold token, a gear that several cards make, can be killed to add one Power that pays a symbol of any domain.

Can you save Energy or Power for a later turn?

No. The Energy and Power you add go into your Rune Pool, and every Rune Pool empties at the start of each Main Phase and at the end of each turn. Whatever is still in the pool at that moment is lost.

What you can keep are the runes themselves. A rune can add its Energy or Power at any moment you have to pay a cost. During your opponent's turn, a rune you left ready can be exhausted for Energy to pay for an Action or a Reaction. Any rune on your board, ready or exhausted, can be recycled for Power at that moment as well.

Which cards add Energy and Power, or change what a card costs?

Many cards do. Energy Conduit, a Mind gear, can be exhausted to add 1 Energy, like an extra rune that never leaves the board. Seal of Rage costs no Energy and one Fury Power, and once it is in play you can exhaust it to add one Fury Power without recycling a rune. It readies with your runes at the start of each of your turns.

Two gear from Spiritforged trade one resource for the other. When you exhaust Hextech Anomaly, you pay any amount of Power to add that much Energy. Ancient Henge works the other way round: when you exhaust it, you pay any amount of Energy to add that much Power of any domain, so exhausted runes can pay a Power cost without leaving the board.

Most cards that lower a cost lower only one of the two parts. Sky Splitter costs 8 Energy and one Fury Power, and its Energy cost drops by the highest Might among your units, but the Fury Power must still be paid. Some cards check both parts: Defy counters a spell that costs no more than 4 Energy and no more than one Power, so it cannot counter Falling Star, which costs only 2 Energy but two Fury Power.

What does the difference mean when you build a deck?

The Energy costs decide when you can play your cards, since you get two runes a turn, and a good Energy curve spreads those costs over the turns of a game. The Power costs decide how many runes of each domain you bring. A Jinx deck full of Fury cards like Falling Star does better with more Fury Runes than Chaos Runes among its 12, and counting the Power symbols of each domain among its cards is where the split of its 12 runes starts.

The game works out the total cost of a card before you pay any of it, so you know how much Energy and Power to add before you use a rune, and how runes pay for cards follows that payment from the first exhausted rune to the last recycled one. The runes page lists the runes of every domain, and the deck builder shows the Energy curve and the 12 runes of a deck while you build it.